Aetobatidae, Myliobatidae, Mobulidae, Rhinopteridae: eagle rays, mobulids, cownose rays. These have a small dorsal fin on the base of the tail. The head is elevated above the pectoral fins and the eyes and spiracles are lateral on head. Tooth‐plates are made up of six‐sided teeth in a horizontal arrangement. They are capable of leaping into the air. The mobulids, which include manta rays (Manta spp.), have cephalic lobes that are cranial extensions of the pectoral fins and assist in feeding. These animals also have gill rakers. Mobulids lack venomous barbs.
Dasyatidae: whiptail stingrays. These inhabit freshwater and saltwater habitats. They have a long and slender tail.
Potamotrygonidae: river stingrays. These are all freshwater species and show a reduced rectal gland. Their venom is more potent than saltwater species.
Torpediniformes (Electric Rays)
These are rays with strong electric organs derived from branchial musculature. They are dorsoventrally flattened with rounded pectoral fins. They are slow‐moving, and do not use their pectoral wings much for locomotion. The skin is soft with no denticles or thorns. Their eyes are very small. There is a well‐developed caudal fin (Nelson et al. 2016).
Pristiformes (Guitarfish and Sawfish)
Guitarfish (Rhinobatidae) have a stout tail, with two dorsal fins, and a caudal fin without a barb. Bowmouth guitarfish (Rhina ancylostoma) are similar but their tail is bilobed and their rostrum is unique. The sawfish (Pristidae), also known as carpenter sharks, have a rostrum shaped like a flat blade with non‐replaceable “teeth” (modified dermal denticles) embedded on the sides (Nelson et al. 2016). The mouth and nares are ventral. Oral dentition varies but teeth are mostly blunt‐edged “cobblestones” in rows. Spiracles are prominent. There are no anal fins.
Acknowledgments
Many thanks go to individuals who were instrumental in the management of this document: Carlos Rodriguez, Charlene Burns, Kevin Maxson, Shane Boylan, Jennifer Dill‐Okubo, and Catharine Wheaton.
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